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Local Structure of High Performance TiO x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy
Author(s) -
Mochizuki Takeya,
Gotoh Kazuhiro,
Kurokawa Yasuyoshi,
Yamamoto Takahisa,
Usami Noritaka
Publication year - 2019
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201801645
Subject(s) - materials science , passivation , electron energy loss spectroscopy , annealing (glass) , heterojunction , electrical resistivity and conductivity , transmission electron microscopy , energy conversion efficiency , high resolution transmission electron microscopy , silicon , solar cell , spectroscopy , analytical chemistry (journal) , optoelectronics , chemical engineering , nanotechnology , layer (electronics) , composite material , chemistry , physics , engineering , quantum mechanics , chromatography , electrical engineering
Recent increases in the power conversion efficiency of crystalline silicon (c‐Si) heterojunction (SHJ) solar cells are due to implementation of carrier‐selective contacts (CSCs) with high passivation performance and low contact resistivity. These electrical properties of CSCs significantly depend on the nature of the CSCs/c‐Si interface at the atomistic scale, and precise control of the interface with the SiO x interlayer is the key to obtaining superior electrical properties. It is shown that a TiO x /c‐Si structure with an interlayer prepared by nitric acid at room temperature shows the best performance among points with five different interlayer formation methods. The underlying mechanisms are investigated by combining high‐resolution transmission electron microscopy and electron energy loss (EEL) spectroscopy. The EEL spectra reveal that the Si:O ratio of an as‐deposited SiO x interlayer is nonstoichiometric ( x < 2), which could contribute to lower contact resistivity. Furthermore, the as‐deposited SiO x leads to formation of a Ti containing SiO x layer with few oxygen vacancies after forming gas annealing, resulting in the significant enhancement of passivation performance. These results show that the control of the interlayer with atomistic scale is of crucial importance to realize higher power conversion efficiency of SHJ solar cells.